Profiles in Geekdom: The hunt for another 'Earth'

Elizabeth Fish |
March 24, 2011

Some of the people who look at how galaxies were created are astrophysicists, such as Rob Crain.

SAN FRANCISCO, 24 MARCH 2011 - The universe is a pretty expansive matter, and it takes years of patient researching by various scientists to find even the smallest of discoveries to answer burning questions about space and galaxies. Some of the people who look at how galaxies were created are astrophysicists, such as Rob Crain.

Born in the UK, Rob studied physics at Durham University, and soon after earned his PhD in the astronomy field. He currently lives in Melbourne, Australia, working at the Centre for Astrophysics and Supercomputing of Swinburne University. His job has allowed him to travel all over to look into galaxy formations, as well as lecture, co-write research papers, and appear on the covers of various scientific journals. Next month, Rob travel to Hawaii to collect data from two very distant galaxies and use the world's best telescope at the Keck Observatory. That also means he'll get to fire a pretty big laser into the sky.

Rob took some time out of his busy schedule to speak to GeekTech about distant galaxies, possible near-future discoveries, and that big laser.

GeekTech: How did you get into the field of astrophysics?

Rob Crain: I did a physics degree at Durham, which has one of the largest astronomy groups in the world. I took a few elective astronomy modules and got hooked. In my final year I did a year-long project, and was lucky to get assigned a supervisor who happened to be very big in the field, and also an excellent teacher. I loved it, and decided I wanted to carry on with research, so applied for PhD positions in the UK. In the end Durham offered me a studentship working on exactly the kind of thing I wanted, so I stayed and got my PhD late in 2008.

GT: Your Pulsar profile says you are a "postdoctoral astrophysicist". What do you do currently?

RC: A "postdoc" is a short term (2-5 year) position that you take between finishing your PhD and getting a permanent "faculty" position. My main research area is the use of supercomputers to generate models of how galaxies form and evolve. In general, we have a good general impression of how galaxies form, but the fine details are still unresolved. Astronomy is a unique science, in that it's driven purely by observation rather than experimentation--you can't just build a new planet, star, black hole, galaxy or universe in a lab--so generating models with supercomputers is the closest we can get to "experimenting."

I also dabble in the more traditional astronomer's task of observing.

GT: Why did you decide to move to Melbourne?

RC: As I was finishing my PhD, I was offered my present job, which involved being able to continue a lot of the research I was doing as a graduate student, since the university here has its own very large supercomputer. Also, science funding in Australia right now is fantastic, providing lots of opportunities for research and sparking big new projects. For example the world's best radio telescope is currently under construction in the Western Australian desert (far from interference from televisions and mobile phones). Melbourne is also a fantastic city to live in, though I'll be moving back to Europe in a few months, as I have a new job in the Netherlands, similar to the one I have now.

GT: What have been the highlights of your career so far?

RC: Swinburne, where I currently work, is the only institute in the world where someone in a junior position (like I am) is even eligible to apply for observing time on the Keck telescopes -- usually you have to be an established professor. So going to Keck (and being in Hawaii) on the strength of my own science proposal last year was very rewarding. Also, late last year an image from one of my simulations was featured on the front cover of the prestigious journal Nature, which was an ambition of mine that I didn't think I'd ever achieve, let alone so early in my career.

GT: You are about to head over to Hawaii to collect data on galaxies. What does this mean you will be doing (and discovering!)? What do you personally hope to find?

RC: Over the last 15 years or so, astronomers have deduced that the early Universe (say, 10 billion years ago) was forming stars and galaxies at a rate 10 times higher than it is now. With all the financial turmoil of the GFC, there were lots of bad jokes about the Universe also being in a recession (cringe). We're trying to find out why the formation of galaxies has slowed up over the last few billion years.

This requires us to peer inside galaxies, at the small "nurseries" where stars are born, to get an idea of the physics at work. Observing these nurseries is easy to do in the local Universe--you've probably seen pictures of these from the Hubble Space Telescope--but for distant galaxies it's very hard. As you probably know, because the speed of light is not infinite, when we look at distant galaxies, we're seeing them as they were in the past. So in order to observe galaxy formation as it was several billion years ago, we need to look at really, really distant galaxies. So even with the gigantic 10-meter mirror on the Keck telescopes, it's a challenge to see the galaxies at all, let alone study their stellar nurseries, because they are so faint and so small on the sky.

In general, people are waiting for the next generation of 30-40-meter telescopes--due around 2020-2025 at a cost of about $1.5 billion--to have a hope of figuring all of this out. But occasionally the Universe lends a helping hand. One of Einstein's greatest achievements was the prediction that matter deflects light. It's a tiny, tiny effect such that on Earth you never notice it, but if you have a massive enough object, the effect can be strong. The most massive "objects" in the Universe are things called galaxy clusters -- areas where many galaxies congregate under their own gravity, and that of huge amounts of cosmic dark matter associated with the galaxies (pictured below). They have masses about 1015 times that of the Sun.

The yellow-ish galaxies are all relatively close together in a galaxy cluster. The strange blue arcs that appear to be rotating around the cluster are in fact images of galaxies that are far behind the cluster (so the cluster is in-between the blue galaxies and us on Earth). The cluster has "lensed" the galaxies; it's a bit like staring at something through the bottom of a wine glass. You see these arcs rather than a perfectly magnified image because, like the wine glass, the cluster is not a perfect lens. However, this lensing effect is hugely useful. Without the cluster in that image, you'd never see those blue galaxies, they'd be too small and faint.

In effect, the cluster turns your 10-meter telescope into a 30-meter telescope, for free, and you can beat the competition to a result by 10 years! The trade-off is that you have to spend a long time looking for galaxies that are aligned just right with galaxy clusters to get lensed. You also have to figure out how to 'un-do' the distorting effect of the lens, to reconstruct what the galaxy would like without the lens in the way. Anyway, the hope is that we'll collect a lot of data about the first stellar nurseries in the Universe, and figure out why they formed stars more efficiently than those we see today.

GT: Can you tell me more about the powerful laser you will get to use in Hawaii?

RC: One of the reasons the Hubble Space Telescope has been such a success is that it orbits above the Earth's atmosphere, and so its images are razor-sharp. Images taken from ground-based observatories are blurred by the distorting effect of the turbulent atmosphere. But we can partially correct for this distortion by rapidly deforming telescope mirrors to precisely counteract the atmosphere - a bit like giving the telescope a new set of glasses, hundreds of times a second. In order to know how to deform the mirror, we need to know how the atmosphere is affecting the light we receive from galaxies. To do this, we fire a laser (the same frequency used in orange street lamps) into the upper atmosphere, where it is scattered by sodium atoms. By measuring the distortion in the scattered light relative to the laser, we know what effect the atmosphere is having, and we can partially correct for it.

GT: Of all the discoveries ever made in space, which do you think has been the most significant?

RC: The first that springs to mind is Copernicus's realization that the Earth wasn't the center of the Universe, as this had profound effects both scientifically and culturally. More recently, people are often surprised to learn that it was only in the 1920s that Edwin Hubble proved there were galaxies other than the Milky Way, and that the Universe is expanding. New evidence in the last few years has surprised even the astronomers, because it suggests that the Universe's expansion from the Big Bang is speeding up rather than slowing down, hinting at new fundamental physics that we don't understand. But I think what will have the biggest effect on us in modern times will be the discovery of another planet similar to Earth. The rate of progress in planet hunting suggests that such a discovery will be made in the near future.

GT: As for the rest of your career, what do you hope you will be able to discover out there?

RC: Big discoveries are fairly few and far between, and progress is more commonly made in small steps. I think most astronomers are keen to keep making their small contribution to our knowledge of the Universe. New telescopes and ever more powerful supercomputers mean that there are always new and exciting discoveries to make if you work hard enough. Very few of us see it as a 9-5 job and are happy to work long hours, the pay off being fairly frequent travel to far-off locations to use telescopes and collaborate with international colleagues, and the opportunity to learn something about the Universe before anyone else does.

GT: If readers were hoping to get into astrophysics too, what would you advise is the best way to go?

RC: I'd advise them to speak to people in the field to gauge whether it's the right path for them, as it's a long, demanding (but rewarding) road. One of my colleagues has written an excellent guide for would-be astronomers, which I highly recommend.

You can find out more about what Rob will be doing in the next few months on his profile.